Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of turbine blades. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as for aircraft, including helicopters. In aircraft, gas turbine engines are used for propulsion of the aircraft. In terrestrial applications, turbine engines are often used for power generation.
Gas turbine engines for aircraft are designed to operate at high temperatures to maximize engine efficiency, so cooling of certain engine components, such as the high pressure turbine and the low pressure turbine, may be necessary. Typically, cooling is accomplished by ducting cooler fluid from the high and/or low pressure compressors to the engine components which require cooling. Temperatures in the high pressure turbine are around 1000° C. to 2000° C. and the cooling fluid from the compressor is around 500° C. to 700° C. While the compressor air is a high temperature, it is cooler relative to the turbine air, and may be used to cool the turbine.
Turbine blades generally include interior cooling channels for the cooling air, and may include portions passing through the airfoil main body and the tip of the blade. One prior art design for cooling a blade tip of is shown in FIG. 7. The airfoil 200 is cooled with a serpentine cooling channel having at least one turn 202 defined by an interior wall 204 extending between pressure and suction sidewalls 206, 208 of the airfoil 200. The tip 210 of the airfoil 200 is cooled with a tip channel 212. Another prior art design for cooling a blade tip is shown in FIG. 8. Like the other prior art design shown in FIG. 7, the airfoil 300 is cooled with a serpentine cooling channel having at least one turn 302 defined by an interior wall 304 extending between pressure and suction sidewalls 306, 308 of the airfoil 300. Here, the tip 310 of the airfoil 300 is cooled with peripheral tip channels 312 on the pressure and suction sidewalls 306, 308.